From Microhabitat of Floral Nectar Up to Biogeographic Scale: Novel Insights on Neutral and Niche Bacterial Assemblies.

Microbial model systems are very useful in addressing macro-ecological questions. Two major theories exist to date, to explain the community structure of organisms: (1) the dispersal (neutral) assembly theory which predicts that community similarity decreases with increasing geographic distance, independent of any environmental variables, and (2) the niche assembly theory which predicts that the communities' compositions are more homogeneous among sites characterized by similar environmental conditions. Our study system offered a unique opportunity to investigate the relative role of environmental conditions and spatial factors in shaping community composition. We explored the bacterial community composition (BCC) of Nicotiana glauca floral nectar using the Illumina MiSeq technique at three spatial scales (plants, site, and region) and two taxonomic levels. Floral nectar samples were collected from 69 N. glauca plants at 11 different sites along a 200-km transect in Israel, along three biogeographic regions. A distance decay of BCC was found among all plants throughout Israel, but such pattern was not found among either sites or biogeographical regions. The BCC was also governed by environmental conditions in all examined scales (from the plant up to the biogeographical region). We also found that taxonomic resolution (89 and 97% sequence identity for clustering operational taxonomic units) affected the results of these BCC analyses. Hence, our study revealed that the BCC in N. glauca floral nectar is shaped by both the environmental conditions and the distance between plants, depending on the sampling scale under examination as well as by taxonomic resolution.

Comparison of sputum microbiome of legionellosis-associated patients and other pneumonia patients: indications for polybacterial infections.

Bacteria of the genus Legionella cause water-based infections resulting in severe pneumonia. Here we analyze and compare the bacterial microbiome of sputum samples from pneumonia patients in relation to the presence and abundance of the genus Legionella. The prevalence of Legionella species was determined by culture, PCR, and Next Generation Sequencing (NGS). Nine sputum samples out of the 133 analyzed were PCR-positive using Legionella genus-specific primers. Only one sample was positive by culture. Illumina MiSeq 16S rRNA gene sequencing analyses of Legionella-positive and Legionella-negative sputum samples, confirmed that indeed, Legionella was present in the PCR-positive sputum samples. This approach allowed the identification of the sputum microbiome at the genus level, and for Legionella genus at the species and sub-species level. 42% of the sputum samples were dominated by Streptococcus. Legionella was never the dominating genus and was always accompanied by other respiratory pathogens. Interestingly, sputum samples that were Legionella positive were inhabited by aquatic bacteria that have been observed in an association with amoeba, indicating that amoeba might have transferred Legionella from the drinking water together with its microbiome. This is the first study that demonstrates the sputum major bacterial commensals and pathogens profiles with regard to Legionella presence.

Izhakiella capsodis gen. nov., sp. nov., in the family Enterobacteriaceae, isolated from the mirid bug Capsodes infuscatus.

Gram-stain-negative, oxidase-negative, facultatively anaerobic, motile, rod-shaped, non-pigmented bacterial strains (N6PO6T, N8PO1 and N8PI1) were isolated from the mirid bug Capsodes infuscatus captured on Asphodelus aestivus plants. The 16S rRNA gene sequences of the strains shared 94.7-95.7 % similarity with species of the genus Pantoea and 95.6 % or less with species from other genera in the family Enterobacteriaceae. A polyphasic approach that included determination of phenotypic properties and phylogenetic analysis based on 16S rRNA, rpoB, gyrB and atpD gene sequences supported the classification of strains N6PO6T, N8PO1 and N8PI1 as representing a novel species of a new genus in the family Enterobacteriaceae. Strain N6PO6T, and the two reference strains of the novel species, grew at 1-37 °C, and in the presence of NaCl (up to 7.5 %, w/v) and sucrose (up to 60 %). Their major cellular fatty acids were C16 : 0, C17 : 0 cyclo, C18 : 1ω7c, summed feature 2 (C14 : 0 3-OH and/or iso-C16 : 1 I) and summed feature 3 (C16 : 1ω7c and/or iso-C15 : 0 2-OH). The DNA G+C content of strain N6PO6T was 49.9 mol%. On the basis of phenotypic properties and phylogenetic distinctiveness, the mirid bug isolates are classified as representing a novel species in a new genus Izhakiella, in the family Enterobacteriaceae, for which the name Izhakiella capsodis gen. nov., sp. nov. is proposed. The type strain of Izhakiella capsodis is N6PO6T ( = LMG 28430T = DSM 29293T).

High quality permanent draft genome sequence of Phaseolibacter flectens ATCC 12775(T), a plant pathogen of French bean pods.

Phaseolibacter flectens strain ATCC 12775(T) (Halpern et al., Int J Syst Evol Microbiol 63:268-273, 2013) is a Gram-negative, rod shaped, motile, aerobic, chemoorganotroph bacterium. Ph. flectens is as a plant-pathogenic bacterium on pods of French bean and was first identified by Johnson (1956) as Pseudomonas flectens. After its phylogenetic position was reexamined, Pseudomonas flectens was transferred to the family Enterobacteriaceae as Phaseolibacter flectens gen. nov., comb. nov. Here we describe the features of this organism, together with the draft genome sequence and annotation. The DNA GC content is 44.34 mol%. The chromosome length is 2,748,442 bp. It encodes 2,437 proteins and 89 RNA genes. Ph. flectens genome is part of the Genomic Encyclopedia of Type Strains, Phase I: the one thousand microbial genomes study.

Pyridine-type alkaloid composition affects bacterial community composition of floral nectar.

Pyridine-type alkaloids are most common in Nicotiana species. To study the effect of alkaloid composition on bacterial community composition in floral nectar, we compared the nicotine-rich wild type (WT) N. attenuata, the nicotine biosynthesis-silenced N. attenuata that was rich in anatabine and the anabasine-rich WT N. glauca plants. We found that the composition of these secondary metabolites in the floral nectar drastically affected the bacterial community richness, diversity and composition. Significant differences were found between the bacterial community compositions in the nectar of the three plants with a much greater species richness and diversity in the nectar from the transgenic plant. The highest community composition similarity index was detected between the two wild type plants. The different microbiome composition and diversity, caused by the different pyridine-type alkaloid composition, could modify the nutritional content of the nectar and consequently, may contribute to the change in the nectar consumption and visitation. These may indirectly have an effect on plant fitness.

Do honeybees shape the bacterial community composition in floral nectar?

Floral nectar is considered the most important reward animal-pollinated plants offer to attract pollinators. Here we explore whether honeybees, which act as pollinators, affect the composition of bacterial communities in the nectar. Nectar and honeybees were sampled from two plant species: Amygdalus communis and Citrus paradisi. To prevent the contact of nectar with pollinators, C. paradisi flowers were covered with net bags before blooming (covered flowers). Comparative analysis of bacterial communities in the nectar and on the honeybees was performed by the 454-pyrosequencing technique. No significant differences were found among bacterial communities in honeybees captured on the two different plant species. This resemblance may be due to the presence of dominant bacterial OTUs, closely related to the Arsenophonus genus. The bacterial communities of the nectar from the covered and uncovered C. paradisi flowers differed significantly; the bacterial communities on the honeybees differed significantly from those in the covered flowers' nectar, but not from those in the uncovered flowers' nectar. We conclude that the honeybees may introduce bacteria into the nectar and/or may be contaminated by bacteria introduced into the nectar by other sources such as other pollinators and nectar thieves.

Transfer of Pseudomonas flectens Johnson 1956 to Phaseolibacter gen. nov., in the family Enterobacteriaceae, as Phaseolibacter flectens gen. nov., comb. nov.

Pseudomonas flectens Johnson 1956, a plant-pathogenic bacterium on the pods of the French bean, is no longer considered to be a member of the genus Pseudomonas sensu stricto. A polyphasic approach that included examination of phenotypic properties and phylogenetic analyses based on 16S rRNA, rpoB and atpD gene sequences supported the transfer of Pseudomonas flectens Johnson 1956 to a new genus in the family Enterobacteriaceae as Phaseolibacter flectens gen. nov., comb. nov. Two strains of Phaseolibacter flectens were studied (ATCC 12775(T) and LMG 2186); the strains shared 99.8 % sequence similarity in their 16S rRNA genes and the housekeeping gene sequences were identical. Strains of Phaseolibacter flectens shared 96.6 % or less 16S rRNA gene sequence similarity with members of different genera in the family Enterobacteriaceae and only 84.7 % sequence similarity with Pseudomonas aeruginosa LMG 1242(T), demonstrating that they are not related to the genus Pseudomonas. As Phaseolibacter flectens formed an independent phyletic lineage in all of the phylogenetic analyses, it could not be affiliated to any of the recognized genera within the family Enterobacteriaceae and therefore was assigned to a new genus. Cells were Gram-negative, straight rods, motile by means of one or two polar flagella, fermentative, facultative anaerobes, oxidase-negative and catalase-positive. Growth occurred in the presence of 0-60 % sucrose. The DNA G+C content of the type strain was 44.3 mol%. On the basis of phenotypic properties and phylogenetic distinctiveness, Pseudomonas flectens Johnson 1956 is transferred to the novel genus Phaseolibacter gen. nov. as Phaseolibacter flectens gen. nov., comb. nov. The type strain of Phaseolibacter flectens is ATCC 12775(T) = CFBP 3281(T) = ICMP 745(T) = LMG 2187(T) = NCPPB 539(T).

Structure of bacterial communities in diverse freshwater habitats.

The structures and dynamics of bacterial communities from raw source water, groundwater, and drinking water before and after filtration were studied in four seasons of a year, with culture-independent methods. Genomic DNA from water samples was analyzed by the polymerase chain reaction - denaturing gradient gel electrophoresis system and by cloning of the 16S rRNA gene. Water samples exhibited complex denaturing gradient gel electrophoresis genetic profiles composed of many bands, corresponding to a great variety of bacterial taxa. The bacterial communities of different seasons from the four sampling sites clustered into two major groups: (i) water before and after filtration, and (ii) source water and groundwater. Phylogenetic analyses of the clones from the autumn sampling revealed 13 phyla, 19 classes, and 155 operational taxonomic units. Of the clones, 66% showed less than 97% similarities to known bacterial species. Representatives of the phyla Proteobacteria, Bacteroidetes, and Actinobacteria were found at all four sampling sites. Species belonging to the phylum Firmicutes were an important component of the microbial community in filtered water. Representatives of Enterobacteriaceae were not detected, indicating the absence of fecal pollution in the drinking water. Differences were found in the bacterial populations that were sampled from the same sites in different seasons. Each water habitat had a unique bacterial profile. Drinking water harbors diverse and dynamic microbial communities, part of which may be active and resilient to chlorine disinfection. This study provides, for the first time, basic data for uncultivable drinking water bacteria in Israel.